News items

As the American Southwest grows hotter, the risk of severe, long-lasting megadroughts rises, passing 90 percent likelihood by the end of the century if greenhouse gas emissions continue at their current pace, a new study says. If we aggressively reduce greenhouse gas emissions, however, we can cut that risk substantially, the authors write.

The Columbia Center for Climate & Life at Lamont-Doherty Earth Observatory has announced its 2016 Fellows. Michael Puma is focusing on food security and climate shocks, and Park Williams is exploring the influence of climate change on droughts and wildfires.

As the second most recent ice age was ending and its glaciers began to retreat, the Earth experienced a large, abrupt climate change that shifted the thermal equator southward by about 4 degrees, according to a new study that for the first time tracks that shift in millennial detail, showing how the Northern Hemisphere cooled and the Southern Hemisphere warmed over the span of a few hundred years. The change would have affected the monsoons, today relied on to feed more than half the world’s population, and could have helped tip the climate system over the threshold for deglaciation, said lead author Allison Jacobel.

Geochemists Alexander van Geen and Jacob Mey helped coauthor a recent paper in the leading journal Science showing that warming climate in the future may not degrade oxygen supplies in some parts of the oceans as previously thought.

A delay in the summer monsoon rains that fall over the southwestern United States and northwestern Mexico is expected in the coming decades according to a new study in the Journal of Geophysical Research. The North American monsoon delivers as much as 70 percent of the region’s annual rainfall, watering crops and rangelands for an estimated 20 million people.

Summers on the Norwegian archipelago of Svalbard are now warmer than at any other time in the last 1,800 years, including during medieval times when parts of the northern hemisphere were as hot as, or hotter, than today, according to a new study in the journal Geology.

Decades of drought, interspersed with intense monsoon rains, may have helped bring about the fall of Cambodia’s ancient Khmer civilization at Angkor nearly 600 years ago, according to an analysis of tree rings, archeological remains and other evidence.

O. Roger Anderson is a microbiologist at Lamont-Doherty Earth Observatory who studies bacteria, amoebas, fungi and other microorganisms. Lately he has been thinking about how tiny organisms that inhabit the vast northern tundra regions could contribute to changing climate, since, like humans, they breathe in oxygen and breathe out carbon dioxide.

The world’s oceans are growing more acidic as carbon emissions from the modern world are absorbed by the sea. A new film, “A Sea Change,” explores what this changing chemistry means for fish and the one billion people who rely on them for food. This first-ever documentary about ocean acidification is told through the eyes of a retired history teacher who reads about the problem in a piece in The New Yorker and is inspired to find out more. His quest takes him to Alaska, California, Washington and Norway to talk with oceanographers, climatologists and others.

The vast majority of the world’s glaciers are retreating as the planet gets warmer. But a few, including ones south of the equator, in South America and New Zealand, are inching forward. A new study in the journal Science puts this enigma in perspective.